The present invention relates to a marine vessel, and in particular to a catamaran vessel. More specifically, but not exclusively, the invention relates to a catamaran vessel for high-seas applications for naval and maritime character.
Catamaran vessels are known. They have two separate hulls which are located at opposite lateral sides of the central longitudinal axis of the vessel. The hulls are connected by a structure known as a catamaran bridge. It is also known to provide the hulls of such catamaran vessels with bulbous forefeet whose shape frames are curved eliptically, circularly or in an analogous manner. It contradistinction to single-hull vessels, when bulbous forefeet are used on the hulls of a catamaran vessel the flow direction of water relative to the forefoot of each hull includes an angle with the elongation of the hulls if the hulls or the forefeet themselves are inclined relative to one another and thus with reference to the central longitudinal axis of the vessel, or if they are asymmetrically configurated. The angle of the water flowing towards the rear of the vessel, i.e. the angle included between the flowing water and the central longitudinal axis of the vessel, is influenced by the degree of inclination of the hull or the bulbous forefeet with reference to this axis, or by the degree of asymmetry, by the configuration of the bulbous forefeet, by the position of the bulbous forefeet with reference to the central longitudinal axis of the vessel, and primarily by the waterline configuration of the hulls and their position relative to one another. This is explained in detail in Saunders, Vol. 1, 1957, pages 279 ff.
When the water flows towards the bulbous forefeet at such an angle, for example from the outer lateral side of the hulls inwardly towards the longitudinal central axis of the vessel, it has been observed that at the inwardly facing side of the respective bulbous forefoot the stream of water lifts off the forefoot and that this leads to the formation of substantial eddies, an effect which is strengthened by the fact that at each bulbous forefoot the water flow is separated into an upper flow and a lower flow and that both of these flows form at the location where they lift off the surface of the bulbous forefoot, respective eddies which, coming in part from above and in part from below, merge again at the inwardly facing side (i.e. the side facing towards the central longitudinal axis of the vessel) of the bulbous forefoot, as producing even stronger eddies. There is therefore a very substantial turbulence in the water that passes through the channel defined between the two elongated hulls and this is disadvantageous in terms of the passage of the vessel through the water.